I. Zawieja
Czestochowa University of Technology, Faculty of Infrastructure and Environment, Institute of Environmental Engineering, Częstochowa, PL

BIOGAS FROM EXCESS SLUDGE SUBJECTED TO THERMOPHILIC METHANE FERMENTATION


The temperature at which the methane fermentation process is carried out affects the rate of biochemical reactions, on the physico-chemical state of the protein and nucleic molecules contained in the sludge. The rise of temperature above the value at which the structure of enzymatic proteins is inhibited causes the metabolic reactions to be inhibited. The optimum for absolute thermophiles is 60 ÷ 75 oC, with a minimum of 40-55 oC. Termofile in its structure contain saturated fatty acids, phospholipids and carotenoids. The proper structure of the cell membrane and enzymes is influenced by thermophilic bacteria resistance to high temperature. Thermophilic conditions accelerate the transformation occurring during methane fermentation, affect the increase of volatile fatty acids, which directly determines the intensity of biogas production. The aim of the research was to determine the effect of methane fermentation under thermophilic conditions on the intensity of biogas production. The studies showed that 31.82 and 38.56 dm3 of biogas were produced as a result of the process at 50 and 55 oC. Methane fermentation under mesophilic conditions (37 oC) yielded a total of 21.43 dm3 of biogas. The increase in process temperature did not affect the methane content of biogas, both for mesophilic and thermophilic conditions during the intensive biogas production phase, the volume of methane was 70 to 80%.

Keywords: thermophilic methane fermentation, biogas, methane